THE Government will face a ferocious barrage in the Commons this week over its handling of the Dounreay crisis, after Scottish Secretary Donald Dewar confirmed yesterday the existence of a report in March recommending closure of the Caithness plant, writes Robbie Dinwoodie.

Mr Dewar tempered his admission with the claim: ''It did not necessarily reach us in March,'' fuelling speculation about differences of opinion between his department, the Foreign Office, the Department of Trade and Industry and the UK Atomic Energy Authority.

His opponents, particularly the Nationalists, buoyed up at their Perth conference, promised an endless onslaught over the affair. q Do-it-yourself household repairs product Polyfilla was used to convert highly-radioactive liquid wastes into a solid form before being dumped into Dounreay's 213-ft deep water filled shaft. Ordinary plaster-of-Paris was also mixed with ''intermediate level'' liquids containing the potentially deadly man-made metal plutonium, an official Atomic Energy Authority report reveals.